Bike is missing on the right side at mid to high RPMs

asdfqwer426

asdfqwer426

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Mora, MN
I've had this issue the last few years and feel like I've replaced just about everything - however I'm at the point where I'd like to just go back to square one and take any and all advice from the pros here.

It's a 72 CL350, engine rebuilt about ten years ago now and only a few thousand miles put on it. last year I got brand new Honda air filters to rule those out, This season I got a brand new battery to rule that out. I just set the static timing (which seemed to be off - which it shouldn't have been because I should've set it last year...) and got it spot on. cleaned the carbs but the after getting all together the right wasn't firing - I took the right carb back off and re-cleaned it, carefully reinspecting the diaphragm for any cracks because I haven't this year (looks great to me). Now the right fires up and idles fine, but seems to stop firing at mid to high RPMs once I start moving.

I replaced the coils a year or two ago trying to track down this exact same problem so I don't think that's the issue.

I'm open to any and all suggestions - I miss driving my 350 and I'm not gonna go another summer without it!

Thanks,
Nick
 
Are the float heights set properly? And the throttle cables are synched? Fuel flowing well to the right carb?

I once had a similar issue on my 450. In my case, I had neglected to synch the cables and one bowl was going dry, causing the cylinder to cut out. I could lay off the throttle for a bit and then go again, but it would dry out quickly at high RPM.
 
oh my gosh - literally years trying to find this issue, at least since 2018 - I went to double check the right (much prefer issues on the right on my CL) and I took the float bowl off and found I could slosh the float around.

I got a pinhole in one side of my right float, flooding the right of fuel at mid to high range (and also draining my tank when I forgot to shut off the petcock a couple times over the years). This HAS to be the issue.

I've had to solder a pinhole on my 500T float years ago too, can't believe I missed it for literally YEARS!

I'll get it really cleaned and aired out so I don't blow myself up and solder it up, see if that gets my 350 back on the road.
 
I hope that solves it. A sunk float would usually mean the cylinder gets too much fuel, but that may very well be why it was cutting out. (Opposite of what happened to my 450.)

Good luck!
 
Well, four years later from my last post and I STILL have this issue. I was really doubting my mechanical ability due to not being able to figure this out, but after doing more work on my 500T and entirely going through a 360 this summer, I'm really feeling like I do in fact know what I'm doing on these bikes, and it must be something odd. Hoping to just pick the brains in this group that really know these things and get ideas.

Each time I find an issue, I think I've got it, it doesn't solve it.

The bike starts great, idles all day long, but once I get it above a few thousand RPMs it starts to bog down and misfire on one side. I used to think it was the right, but I'm having a hard time telling for sure.

This summer when troubleshooting I saw a puff of smoke out the left side of the engine, the head gasket was leaking. I thought for SURE this was it. I got a gasket kit, rebuilt the top end with all new gaskets, sorted some muffler mounting issues, recleaned everything and put in new carb o-rings for good measure. it seemed to very briefly run better, like less than a minute, but then the same symptoms turned up.

to recap, I've gone over every bit of the ignition system. I've swapped coils with coils from my 500t. I've tried a new set of points. I tried my spare advance mechanism. the floats are set correctly. compression is good.

I have only one theory left - when i was rebuilding the carbs the main jet on one carb was VERY loose. like it would just fall out of the carb body, even with a new o-ring in it. I thought it would likely swell a bit with gas and seal ok, especially with the retaining bit holding it on with the float bowl on, but now I'm wondering if that worn out carb body isn't just letting too much gas through when it gets to higher RPMs. I replaced plugs this year after the top end rebuild and there was definitely one side that was darker than the other, both piston crowns, and plugs, so one side is definitely running rich and seems to fit with my idea.

I already have another new carb kit that came in the mail and I plan to rebuild them. again. and take a closer look at that carb body I mentioned.

If that is the case, does anyone have any suggestions for how to fix that short of just buying a new carb body (which I actually did try at one point, but that ebay special had other issues itself)? Maybe try to find a larger o-ring, but I would prefer something that lets me use normal carb kits in the future.
 
Just looking at odd ball stuff here.

Have you replaced the condensers or at least swapped from left to right to see if the miss follows it?

Vibration at higher RPM's causing a loose connection in the ignition at a connector or a solder joint?

When you rebuilt the top end did you do a valve job or and confirm the valve stems were straight? A slightly bent valve stem might stick enough at higher RPMs to cause a miss? ( Hate to even mention that as you have just did a top end rebuild)
 
It's been years I've been tracking this down, but like 5 years ago I got new coils and condensers. I also swapped the whole coil/condenser pack from my 500T. I swear I also swapped them left to right to check that too.

The bad electrical connection did cross my mind, but I haven't done much with that other than to follow voltage from battery through all the switches all the way to the coil plugs and voltage was steady, so no dirty switches or plugs, but vibrations at speed in other connectors could be a possibility. I was thinking of running a bodge wire from the battery + directly to the coils just to rule out everything along the way.

I did not mess with the valves. I will look through electrical and the carb thing I mentioned before pulling it back apart, but I'll take all suggestions at this point. Thanks!
 
Sounds like you've eliminated everything with the exception of that carb - even a tiny amount of fuel seeping past the jet would certainly affect that mixture. With higher RPM creating more vacuum it may only present itself there. The only other thing I can think is excessive dwell on one side of the points.
 
I'd like to hear the bogging, if possible.

With the bike idling, try lifting the throttle arm on one side at a time. Is the behavior the same on each side? If not, how do they differ?
 
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